The IIHF is the international governing body but they have very little clout regarding this and mostly just handle transfer agreements between the leagues in different countries and run the non-Olympic international tourneys (World Championships, World Juniors, etc.)
NHL and the NHLPA have to agree for the players to go to the Olympics every 4 years. And there's a building sentiment that its not going to happen in 2018 since the Olympics are in a non-NHL talent nation in South Korea (we miss you, Richard Park!

) The owners dislike it because it breaks up the season and puts their million dollar investments at risk (*cough* John Tavares *cough*). From what I've heard, the players are really indifferent about it.
IMO the Olympics should always be an amateur endeavor. That's what made 1980 so special, and the legendary Canada/Sweden gold medal shootout game in '94 was like a future stars game. Most of the world really doesnt follow Junior hockey so this is a good chance to get exposure for the young up and coming stars.
There was also something cool about watching Team USA and Team Canada scrimmage the NHL teams in the lead up to the Olympics.